Sealing means for a slidable member in a pressure unit



J. MERCIER Dec. 18, 1956 SEALI-NG MEANS FOR A SLIDABLE MEMBER IN A PRESSURE UNIT United States Patent O SEALING MEANS FOR A SLIDABLE MEMBER IN A PRESSURE UNIT Jean Mercier, New York, N. Y.

Application January 22, 1954, Serial No. 405,581

Claims priority, application France July 4, 1953 4 Claims. (Cl. 286-26) This invention relates to the sealing means for a slidable member in a pressure unit and more particularly to sealing means including a resilient ring type seal.

As conducive to an understandingof the invention it is noted that where a single resilient ring type seal, such as an O ring is used, the eiectiveness of such sealis poor when the pressure on opposed sides of the O ring is identical, for such seal only operates effectively when there is greater pressure on one side than the other.

Where there is a difference between the pressures -on lopposed sides of an O ring and these pressures should reverse, at the moment when both pressures are equal,

`the sealing eifect will be poor.

rings will rise due to the slight leakage past they rings.

lf -such pressure, which is applied tothe adjacent sides of the two O rings, should increase to an amount equal to the pressures on the other sides of both ofthe O rings, no dependable seal would be afforded between the two charnbers defined in the accumulator by the piston.

-Itis accordingly among the objects of the invention to provide sealing means, including at least 1one O ring, for the slidable member of; a pressure unit which will insure that at substantially all times in normal operation of the unit, the pressure on one side `of -said 0 ring will be less than the pressure on the other side of said O ring for dependable sealing action, and which will prevent eX- trusion and injury to such O ring by relieving the pressure thereagainst, which sealing means is simple in construction using substantially conventional components, none `of which are delicate or likely to become deranged even with long periods of use, and which will substantially preclude leakage of uid under pressure from one side of the sealing means to the other.

According to the invention from its broader aspect, the g sealing means comprises at least two resilient seals, one of which is an O ring and whichare associated with a sliding member which may be subjected to ditferent pressures thereagainst on theportions thereof on opposed sides of the sealing means, and meansY are provided to dis- L charge fluid from the space between the two seals when a predetermined pressure has been attainedtherein.

According to one embodiment ofthe invention, both of the resilient seals. are O rings encompassing a piston Slidably mounted in a pressure accumulator and defining i f a chamber therein on each side, for gas and oil, and an annular groove is defnedbetwen the two O rings. Both of the O rings are positioned in associated annular grooves and the groove adjacent the end of the piston nearest the chamber of the accumulator which isV charged with oil under pressure, is elongated and is in communication with such chamber by means of a passageway extending through the piston and leading into the 4end of the annular groove adjacent saidzpiston end. More. particularly, the elongated annular grooveis of width at its inner end such that the 0 ring will t snugly andv is of width Patented Dec. 18, 1956 ICC at its outer end suicient for the O ring to fit loosely therein.

According to another embodiment of the invention, the slidable member is a piston rod encompassed by the 0 ring and by a resilient sleeve having a lip resiliently retained against the pist-on rod also t-o provide a seal.

Divisional application Serial No. 565,025, filed February 13, 1956, covers the constructions shown in Figs. 1 to 3 of the drawings.

v ln the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. 1 is a longitudinal sectional view of a piston accumulator according to one embodiment of the invention,

Figs. 2 and 3 are longitudinal sectional views of piston accumulators according to other embodiments of the invention, and

Fig. 4 is a longitudinal sectional View of a shock absorber according to still another embodiment of the invention.

Referring now to the drawings, in the embodimentv shown in Fig. l, the pressure relief means is incorporated in a pressure accumulator comprising a substantially cylindrical container 11 having plugs 12 and 13 screwed in each end thereof, said plugs having al gas inlet port 14 and a iluid port 15, respectively.

Slidably mounted in the container 11 is a piston 16 dening a gas chamber 17 and a iluid chamber 18 in communication with the ports 14 and 15, respectively.

The piston has a pair of peripheral annular grooves 21 and- 22 in each of which is positioned a resilient sealing member, preferably an O ring 23 and l24 to provide a seal between the piston and the inner surface of the container 11.

The annular groove 22 which is desirably of greater length than groove 21, is 4of width at its inner end 25 slightly less than the diameter of the O ring and at its outer end 26 of greater width than such diameter so that when the 0 ring i-s at the inner end it will t snugly to provide a seal, and when at the outer end, will tit loosely.

The periphery of piston 16 at its end 2S is desirably spaced slightly from the wall ofv container 11 as at 31 to ensure that clearance will be provided therebetween and a plurality of passageways 32 through the end 28 of the piston provide communication between chamber 18 and the wide end 26 of annular groove 22.

Desirably the piston 16 has an elongated annular groove 33 in its periphery between grooves 21 and 22 which may be in communication by means of a passageway 34 with a chamber 35 in the piston.

Before the chambers 17 and 18 are charged, the pressure in such chambers and in annular groove 33 will be atmospheric. When chambers 17 and 18 are charged, for

example, with air and oil under pressure, as the press-ure in groove 33 is still atmospheric, there will be a differential between the pressures on opposed sides of each of the O rings 23 and 24 and consequently they will be forced toward each other wedging into the slight space 36 between the wall of the container 11 and the periphery kof the piston to provide a dependable seal. Thus there will be substantiallykno leakage between the iluids in the chambers 17 and 18.

In use of the unit, a valve (not shown) controlling As long as the pressure in groove 33 remains below that in chambers 17 and 18, the O rings 23, 24 will remain wedged into the spaces 36 to form dependable seals due to the fdiference between Ithe pressure on opposed sides of the O rings.

If the pressure in ygroove 33 should continue to ris-e with repeated operation of .the accumulator and movement of `the piston, with resultant leakage past O ring 24, when such pressure exceeds `the pressure in chamber 18, the O ring will be moved tow-ard the outer end 26 of the annular groove 22. As a result, the O ring will then tilt loosely in the wider end 26 of groove 22 and will no longer form an eiective seal. Consequently the oil under pressure in groove 33 will be forced by the air compressed in such groove out of the clearance 31 and the passageway 32 to relieve the pressure in such groove 33.

The provision of both .the clearance 31 and passageway 32 ensures that one or Ithe other or both will be open for relief of pressure in groove 33.

As 4the pressure 1in .the gas chamber 17 is never less than the minimum pressure attained in chamber 18, it is apparent from the foregoing 'that `the pressure in annular groove 33 will always be less than [that in chamber 17 and hence the O ring 23 will remain wedged in the associated space 36 to form a dependable seal, thereby preventing leakage between chambers 17 and 18.

As the 0 rings iare designed to withstand the maximum pressures utilized in the chambers 17 and 18 without extrusion, and as the movement of O ring 24 will occur before the pressure in groove 33 can rise above such pressure, extrusion of O ring 23 with resultant iniury lthereto is precluded.

hen the piston reaches the upper end of the container 11 shown in Fig. 1, i. e., when all the oil has been discharged from the container, the pressure in chamber 18 will be substantially atmospheric. At this time the O ring 23 will provide a dependable seal as the pressure in chamber 17 will be greater than that in groove 33 which now also is substantially atmospheric.

When the chamber 18 is again recharged with oil under pressure, the O ring 24. will be forced toward the smaller end of groove 22 to wedge into the associated space 36 to again provide a dependable seal. Thus the O ring 2.4 functions as a one-way valve.

The embodiment shown in Fig. 2 is Substantially identical to that shown in Fig. 1 and corresponding parte have the same reference numerals primed.

As shown in Fig. 2, a sleeve 41 is securely mounted in container 11 and is retained at `one end against an annular shoulder 42 in .the container by means of a snap ring 43, for example, reacting .against the other end of the sleeve 41 and retained lin ian annular groove L14 in the wall :of the container.

In order to provide -a seal between the juxtaposed surfaces of the container 11 and the sleeve 41, a resilient sealing ring 45 is positioned in annular groove 46 in the outer periphery of sleeve 41.

Slidably mounted in the bore 47 of sleeve 41 between ports 14 and 15 tis a piston 48, illustratively `a tubular member having at least one of its ends closed as at 49. To provide la dependable seal between the chambers' 17 and 18 on each side of piston 48, a pair of peripheral annular grooves l21 and 22' are provided in 4the inner surface of sleeve 41 adjacent Ithe -ends `of the latter, a yresilient sealing member, prefer-ably an ring 23 and 24', being positioned in each of said grooves respectively. Desirably van `elongated annular groove 33 is provided in sleeve 41 between grooves 21 and 22'. The annular groove 22 which is desirably of greater length than groove 21', is of width at its inner end 2S slightly less than the ldiameter of O ring 24 `and at its outer end 26 :of greater width than such diameter, so that when the 0 ring 24 is at the inner end, it will t snugly to provide a seal and when at the outer end will fit loosely.

The inner periphery of sleeve 41 at its' end 51 is spaced slightly from the piston 48 as at 52 to -ensure `that clearance will be provided therebetween :and a plurality of passageways 32 'through the end 51 of the sleeve provide communication between chamber 18 and the wider end 26' :of :annular groove 22.

As the operation of ythe embodiment of Fig. 2 is sub- 4stantially yidentical to that of Fig. l, it will be out briefly described.

Thus, after continu-ed use of Ithe tirait, if .the pressure in groove 33 becomes greater Ithan that in chamber 18', `the ring 24 will be forced toward the wider end 26 of groove 22' and hence :the liquid under pressure in groove 33 will `discharge through passageway 32 and the clearance 52 into chamber 18 to relieve the pressure in groove 33', thereby preventing extrusion of the O rings.

In the embodiment shown in Fig. 3, in which three seals are provided, ithe pressure relief means is incorporated 4in a pressure accumulator comprising `a substantially cylindrical container 61 having plugs 62 and 63 screwed in its respective ends, said plugs having a gas inlet port 64 and a fluid port 65, respectively.

Slidably mounted in lthe container 11 is a piston 66 defining :a gas chamber 67 and a uid chamber 68 in communication with the ports 64 `and 65, respectively.

The piston has three spaced annular grooves 78, 71 and 72 in its periphery in each of which is positioned 1a resilient .sealing member, preferably an O ring 73, 74 and 75 rto provide a `seal between the piston and the inner surface of ythe container. In addition, the piston has two elongated annular grooves 76, 77 positioned between grooves 70, 71 and 71, 72 respectively.

The annular groove 70 which is desirably of greater length than grooves 71 and 72, is of width at its inner end 78 slightly less .than the diameter of the O ring and at its outer end 79 of greater width .than such diameter so .that when the 0 ring is at the inner end, it will lit snugly to provide a :seal and when at the outer end will fit loosely.

The periphery of piston 66 at its end 81 is desirably spaced slightly from the wall of container 61 as at 82 to ensure that clearance will be provided therebetween and a plurality of passageways 83 through the end 81 of the piston provides communication between chamber 67 and the wide end 79 of annular groove 70.

The end 84 of piston 66 has a cavity 85, threaded as at 86 at its outer end and a passageway 87 leads from annular groove 77 into cavity 85. The end of passageway 87 in cavity 85 forms a seat for a ball valve 88 which is normally retained on its seat by a coil spring 89 compressed between ball 88 and a bored plug 91 screwed into the threaded end 86 of the cavity 85.

As previously described with respect to the embodiments of Figs. 1 and 2, when chambers 67 and 68 are initially charged with air and oil under pressure, as the pressure in grooves 76 and 77 will initially be atmospheric, there will be a differential between the pressures on opposed sides of the O rings 73 and 75 and consequently they will be forced toward each other, wedging into the slight space 93 between the wall of the container 61 and the periphery of the piston 66, to provide a dependable seal.

In use of the unit, a valve (not shown) controlling the oil port 65 is opened. As a result, the pressure in chamber 68 will drop and by reason of the greater pressure in chamber 67, the piston will move upwardly (Fig. 3) forcing oil from chamber 68.

As a result of such movement of the piston 66, oil from the wall may be forced past seal ring 75 into the annular groove 77 and the pressure in such groove, due to the compression of the air therein, will increase.

As the pressure in groove 77 increases and as the pressure in groove 76 is initially atmospheric, the O ring 74 will then wedge into the associated space 93 to provide a dependable seal at such point. v

As long as the pressure in groove 77 remains below that in chamber 68; and the pressure in groove 76 is less than that in groove 77 and less than that in chamber 67, the three rings 73, 74 and 75 will each wedge into the associated space 93 to form a dependable seal to substantially preclude leakage between chambers 67 and 68.

If the pressure in groove 77 should rise with operation of the unit and movement of the piston and leakage past 0 ring 75, to exceed the pressure in chamber 68, based upon the setting of the spring 89, the ball 88 will be moved 0H its seat for relief of the pressure in groove 77 when it reaches a predetermined amount, and the O ring 75 will move away from the space 93.

When the pressure in groove 77 is relieved, it will fall to the value of the pressure in chamber 68 plus the spring pressure. As there is still a difference in the pressure on opposed sides of the O rings 73 and 74, they will still provide dependable seals to prevent leakage as the O ring 75 moves from space 93 to wedge into space 93 due to the greater pressure now in groove 77 than in chamber 68.

In the event that leakage should occur into groove 76 during movement of the piston and the pressure in groove 76 should exceed that in the chamber 67, the O ring seal 73 will move as previously described in the embodiment of Figs. 1 and 2 to relieve the pressure in such groove. Prior to such movement as the pressure in groove 76 will have risen to exceed that in groove 77, the O ring 74 will wedge into the associated space 93' to form a dependable seal.

It is of course to be understood that the ball valve or other mechanical one-way valve could be connected to groove 76 in place of the elongation of groove 70 and the associated passageway 83 or the groove 72 could be elongated and a passageway 82 provided and the ball valve 88 eliminated.

The construction shown in Fig. 3 also precludes eX- trusion of the O rings with resultant injury thereto and insures a dependable seal to prevent leakage between chambers 67 and 68.

The pressure relief means for a resilient seal may be utilized for the seal Vof sliding means other than the piston of an accumulator.

Thus, in Fig. 4, an embodiment is shown in which pressure relief means is provided for the resilient seal of the plunger of a shock absorber.

As shown in Fig. 4, the unit comprises a cylinder 101 having a plug 102 at one end with an air port 103. Slidingly mounted in container 101 is a piston' 100 to which is connected one end of a plunger rod 104, the piston defining chambers 110, 120 in the container. The free end 105 of the plunger 104 extends through the bore 106 of a plug 107 positioned in the other end 108 of the container 101.

Seated against an annular shoulder 109 in container 101 is a collar 111 which encompasses plunger 104 and against which the plug 107 is urged by means of a cap 112 screwed on the threaded end 108 of the container.

The collar has a cutaway portion 113 in its inner periphery in which is positioned the lateral ange 114 of a sleeve 115 of resilient material suchv as spring steel which encompasses plunger 104. The free end of the sleeve defines a lip 116 normally urged against the plunger to provide a dependable sliding seal.

The bore of plug 107 near its router end has an annular groove 117 in which a resilient seal such as an O ring 118 is positioned and an annular groove 119 is provided in said bore between groove 117 and the inner end of the plug.

The plug 107 may also have a cylindrical sleeve 121 protruding outwardly therefrom which has a lip 122 at one end which snugly engages the plunger 104 to define a sliding seal.

In the operation of the unit shown 'tn-Fig. 4, the chamber is charged with air under pressure. As the groove 119 and the space between seal 118 and lip 116 is initially under atmospheric pressurethe pressure against the outer surface of the sleeve will retain the lip 116 thereof against the plunger 104 to provide a dependable seal. As the pressure against both surfaces of O ring 118 is substantially atmospheric, such .0 ring seal is not effective as a seal at this time.

When the plunger 104 moves during normal use thereof to compensate for shocks thereagainst, there may be slight leakage of oil normally provided in chamber 120 for lubrication purposes, past the lip 116 into groove 119. As a result, the pressure in such groove will increase so that the O ring 118 will be forced into the space 123 by reason of the dilerenoe between the pressure on opposed sides so that both the lip 116 and the O ring 118 will form dependable seals to prevent leakage of oil and gas to the atmosphere.

In the event the pressure in the groove 119 should increase to an amount which approaches the extrusion point of the O ring 118, as the lip 116 is designed to yield at slightly lower pressure, it will do so, releasing the pressure in the annular groove 119 so that at no time will it rise to an amount above the extrusion pressure.

In the event there should also be slight leakage past the O ring 118, the pressure in the space between lip 122 and the O ring would also build up. The lip 122 is also designed to yield to relieve the pressure between lip 122 and O ring 118 before such pressure rises to exceed the pressure in groove 119 so that the O ring 118 will remain wedged in space 123 to provide a dependable seal.

It is apparent from the foregoing that the lips 116 and 122 function as one-way valves to permit discharge therepast only when the pressure exceeds a predetermined amount.

With the constructions herein described, during normal operation of the units, a difference will be maintained between the pressures on opposed sides of the O ring for dependable sealing action, yet without likelihood of extrusion of the 0 ring.

As many changes could be made in the above construction, and many apparently widely different embodiments of .this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings lshall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. Equipment of the character described comprising a container, a plunger slidably mounted in said container, said container having a bore at one end through which said plunger extends, said bore having an annular groove in its inner periphery, a resilient sealing ring in said annular groove encompassing said plunger, a sleeve of resilient material rigidly mounted at'one end with respect to said container adjacent said bore, on the inner side of said ring, extending into said container and encompassing said plunger, the free end of said sleeve dening an annular lip normally resiliently retained against said plunger.

2. The combination recited in claim l in which said bore has a second annular groove in its periphery between said resilient sealing ring and said lip end of said sleeve.

3. The combination recited in claim 1 in which a second sleeve of resilient material is afxed at one end with respect to said container on the other side of said ring, extending outside of said container and encompassing said plunger, the free end of said second sleeve dening an annular lip normally resiliently retained against said plunger.

4. Equipment of the character described comprising a Cylindrical member, a member slidably mounted in said cylindrical member, one of said members having an annular groove, a resilient sealing ring in said annular groove in slidable engagement with said other member, and a sleeve of resilient material encompassing said slidable member and securely mounted with respect to one of said members, the free end of said sleeve dening an annular lip normally resiliently urged against the other member, to provide a seal lwith respect to said slidable member.

References Cited in the le of this patent UNITED STATES PATENTS Seamark Apr. 4, 1944 Edmund May 23, 1944 Kremiller Mar. 11, 1947 Ashton Apr. 20, 1948 Smith July 5, 1949 Greer July 13, 1954 

